"Xenon burners" are actually lamps rather than devices which cause combustion, which lamps operate at very high temperatures and with great radiation intensity so that they appear to involve a combustion process, although the device is simply a high intensity lamp. These xenon lamps are used as a source of high intensity radiation and heat in various devices, particularly apparatus for the accelerated age testing of materials such as fabrics, plastics, and paint films, to determine their useful life under outdoor or other conditions where high temperatures and ultra violet radiation are present. Examples of such testing apparatus are the commercial materials testings systems available from Atlas Electric Devices Co. of Chicago, Ill.
Such high intensity xenon "burner" lamps emit so much energy that they generally include a water cooling system, to avoid melting of the quartz bulb and destruction of other components of the lamp during operation. In the prior art, a closed-loop conduit is provided for circulating water through the xenon lamp, with the circulating water passing through a water reservoir where there are tap water heat exchange coils to provide water/water heat exchange between the circulating water in the reservoir and cold, circulating tap water passing through the coiled tubing in the reservoir. By this means, heat from the xenon lamp may be first transferred to the circulating water, and then removed from the water by heat exchange with flowing tap water in the coiled tubing, prior to recirculating the water to pick up another load of heat from the xenon lamp.
Additionally, a deionizing unit is also provided in the water circulation path, to avoid the deposition of solutes from the water onto water-contacting surfaces of the xenon lamp. Such deposits are undesirable because they reduce the radiation emission characteristics of the xenon lamp, and increase its heat of operation.
Such a prior art cooling system has the disadvantage that it is of course dependent upon an external water source. A xenon lamp can have a power of typically 2800 to 8400 watts, so that a relatively large amount of cooling tap water must pass through the system. Thus, such a system is not desirable for use in areas where there is a water shortage, or where the water pressure is low, or where the water is not cold enough for effective heat exchange. Also, upon the failure of the water supply, the apparatus may not be able to operate, or it may be damaged before it is realized that the water flow has failed.
As another issue, any leak in the heat exchange barrier between the cooling tap water and the recirculating heat exchange water can provide contamination to the heat exchange water. Such an unnoticed, continuous addition of water hardness to the recirculating water system may overwhelm the deionizing unit, and cause deposition of solutes in the xenon bulb. This can force termination of operation of the unit and costly repairs.
By this invention, a lamp cooling system is provided which is not dependent upon a cooling water source. Thus, the system of this invention is much more versatile, being useable in many locations where there is no ready source of water. Also, the unit may be portable for moving around between a variety of locations, without the need for connection with a cooling water source. Likewise, the problem of mineral deposits which may enter the recirculating water system through the cooling water can be eliminated, and no drain line is required, in preferred embodiments. The unit of this invention can, in preferred embodiments, be dependent only on one utility, namely electricity, so that a failure of or the absence of a water supply does not limit its use.
Additionally, the lamp cooling system of this invention can serve, where desired, as a source of more useable heat than a typical water cooled system. In cold weather, the unit may serve not only as a xenon bulb cooling system, but also as a room heating system in the same area, or at a location remote from the xenon bulb, to defray other heating costs.